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SpaceEngineer
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SpaceEngine F.A.Q.

12 Nov 2016 06:51

The main Frequently Asked Questions are here
You may ask other questions in this thread.
 
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Quarior
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SpaceEngine F.A.Q.

23 Dec 2016 03:41

SpaceEngineer wrote:
Source of the post The main Frequently Asked Questions are here

It is the old link, the new link is here (http://spaceengine.org/manual/faq/).

Otherwise, I post here a message but nobody answered me but the question I think it is also in this forum.
How does the coordinates in Space Engine change from XYZ to RA, Dec and Dist and vice versa ?
I tried with Proxima but without succes (see Proxima.ggb (required GeoGebra (free))) and with the version Python (see Coordinated convertor.py (required Python (free)), I just convert XYZ to Dist.
I attach my files and thank for a answer.
Coordinated convertor.zip
Coordinated convertor.py and Proxima.ggb
(33.19 KiB) Downloaded 1 time

Have a good day.
 
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SpaceEngineer
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SpaceEngine F.A.Q.

28 Dec 2016 04:38

Quarior wrote:
Source of the post How does the coordinates in Space Engine change from XYZ to RA, Dec and Dist and vice versa ?


RA/Dec/Dist to xyz:
x = Dist * cos(Dec) * sin(RA);
y = Dist * sin(Dec);
z = Dist * cos(Dec) * cos(RA);


xyz to RA/Dec/Dist
Dist = sqrt(x*x + y*y + z*z);
Dec = asin(y / Dist);
RA  = atan2(x, z);
if (RA >= 2*pi) RA = RA - pi/2;
if (RA <  0)    RA = RA + pi/2;


RA and Dec must be in radians, Dist in parsecs. xyz coordinates in SE are in Equatorial system (you may toggle the equatorial coordinate grid to see that).

Regarding to you question, you can't place a black hole in the exact center of the galaxy using RA/Dec/Dist, because coordinates are stored in fp32 format internally. This mean that they has only 8-9 digits precision. You may type many digits in the script (like RA 3.4681313548866251), but only 8-9 first digits will be used.

Hexadecimal format has a 3-millimeter precision across the entire Universe, but it is used only for camera.
 
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Quarior
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SpaceEngine F.A.Q.

28 Dec 2016 05:36

SpaceEngineer wrote:
SpaceEngineer:Source of the post RA and Dec must be in radians, Dist in parsecs. xyz coordinates in SE are in Equatorial system (you may toggle the equatorial coordinate grid to see that).

Sorry but I don't know for find xyz with the equatorial coordinate grid :
scr00000.jpg
Example with Proxima

And if I use the AbsPosition (in save-user.cfg), I have this error : ValueError: math domain error.
And with Proxima to convert RA, Dec and Dist to XYZ, I have this values :
X = -0.36132180795670715 m
Y = -1.1503733386385426 m
Z = -0.47175350706635627 m
Coordinated convertor.zip
Python code
(1.28 KiB) Not downloaded yet

Thanks in advance for help :)

SpaceEngineer wrote:
Source of the post Regarding to you question, you can't place a black hole in the exact center of the galaxy using RA/Dec/Dist, because coordinates are stored in fp32 format internally. This mean that they has only 8-9 digits precision. You may type many digits in the script (like RA 3.4681313548866251), but only 8-9 first digits will be used.Hexadecimal format has a 3-millimeter precision across the entire Universe, but it is used only for camera.

Too bad :(, I would have tried, I hope it will be corrected in the next version.
 
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SpaceEngineer
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SpaceEngine F.A.Q.

28 Dec 2016 06:49

Quarior wrote:
Source of the post Sorry but I don't know for find xyz with the equatorial coordinate grid :

Why you need this? You can't position stars in SE with accuracy of 3 mm anyway.
 
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Mosfet
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SpaceEngine F.A.Q.

28 Dec 2016 08:02

Just a reminder for these calculations: in SE 0980, Equatorial grid displays shifted values of RA and Dec.
Attachments
scr00003.jpg
"Time is illusion. Lunchtime doubly so". Douglas N. Adams
My mods - My specs: Asus x555ub - cpu i5-6200u, ram 4gb, gpu nvidia geforce 940m 2gb vram
 
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Quarior
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SpaceEngine F.A.Q.

28 Dec 2016 09:13

Mosfet wrote:
Source of the post Just a reminder for these calculations: in SE 0980, Equatorial grid displays shifted values of RA and Dec.

I know but isn't precise.

SpaceEngineer wrote:
Source of the post Why you need this? You can't position stars in SE with accuracy of 3 mm anyway.

Even if we can not set for 3 mm at the moment, for a future version, I would already have the converter Unless you plan a new way to place objects, - of course keeping the current one - due to :
StarBarycenter "Proxima System"
{
AbsPosition (-00000000000000005CF7B4EA659695D7, -00000000000000012819D403B042F965, -00000000000000007978254DF318A650) //Universal position
}
StarBarycenter "Sagittarius system"
{
RefBody "Milkay Way"
RelPosition (0, 0, 0) //Position relative to the RefBody
}


But the last time, you said it was impossible for the second option (except it was with RA, Dec and Dist).
 
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SpaceEngineer
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SpaceEngine F.A.Q.

29 Dec 2016 10:10

It's impossible for both options. As I had said, star coordinates are stored in FP32 format internally, so defining them as 64.64 hexadecimals has no sense. They will be converted to FP32 anyway, with loss of precision.
Second option also deals with loss of precision, because all catalog stars has a coordinate system origin in the Sun. At a distance of a center of the Milky Way, precision loss of FP32 numbers will shift black hole position by many AU. In other galaxies such shift is even more worse.
 
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gamadh
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SpaceEngine F.A.Q.

14 Jan 2017 15:03

And the decrease in the loading time of the planets, in which version will be added?
 
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Mosfet
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SpaceEngine F.A.Q.

14 Jan 2017 17:02

Loading time can be tuned in every version and it also depends on what are the settings used, but let's consider even max settings, that's very dependent to the hardware where the program runs, so there's not really a right answer to this question.
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